The answer
St. John Chrysostom says, “He made mention of the root in no other connection than that they might learn that nothing can be done without His power and that they must be united to Him by faith as the branch is to the vine.”777
Fr. Tadros Yacoub Malaty
Notes
777 St. John Chrysostom, Homilies on John Homily 76 (John 14:31–15:10) (FOTC 41:317).